1. Field of the Invention
The present invention concerns an electrical machine with a stator and a rotor rotatable about an axis of rotation and a method of mounting such an electrical machine on a unit, such as an internal combustion engine.
2. Prior Art
Electrical machines in which the rotor is not mounted on a stator housing and in which no bearing elements are provided to secure the rotor in a rotatable manner relative to the stator or to define the axis of rotation of the rotor are known as bearing-free machines. In operation, electrical machines of this type are always connected with a unit, for example an internal combustion engine or a gearbox. In this case the rotor is connected securely to a shaft of the unit by means of which the position of the rotor inside the electrical machine is determined.
In the case of known electrical machines of this type, before being fitted to the unit the rotor can be moved in any direction relative to the stator. In the case of permanently energized electrical machines, usually strong permanent magnets are secured to the rotor. Thus, when the movable rotor comes into contact with a ferromagnetic part of the stator, it is often difficult to release the rotor from the stator due to the strong magnetic force. Preassembly and shipment of such an electrical machine as a complete unit is not possible for this reason. Costly guiding and centering devices are required to fit the electrical machine to the unit.
It is, therefore, an object of the present invention to provide such an electrical machine which can be shipped and installed easily and to provide a suitable method for mounting such an electrical machine to a unit.